Athletes with relative shortening of the hip flexors and accompanying weakness of hip extensors will exhibit decreased hip extension at terminal stance phase or “toe off.” Athletes who lack hip extension may also exhibit related limitation in great toe extension. Often these athletes will show decreased wear under the great toe aspect of their shoe sole and relative increased wear under the more lateral toes. These athletes may also demonstrate increased hip flexion at initial contact or “heel strike” in an effort to make up for the shorter stride length caused by limited hip extension. In patients with knee instability this will contribute to hyperextension or “giving way” of the knee.13
I recommend finding out what’s really wrong from a professional. But it probably doesn’t take a rocket scientist to discover your core is weak or your butt could use a little muscle tone! :) Here are some exercises you could do in the meantime, or sign up for a Fit Tutor membership to help keep you balanced, strong, and fit! Check out membership options here: Fit Tutor Membership Levels

The rectus femoris is one of the four quadriceps muscles -- the quadriceps are the major muscle group of the front of the upper leg. The rectus femoris attaches to the anterior inferior -- the part toward the feet -- portion of the iliac crest and runs to the base of the patella, also known as the knee. The femoral nerve supplies the rectus femoris with nerves. This is the only muscle that crosses the hip joint, which enables it to work as a hip flexor and a knee extender muscle.

For runners, tight hip flexors prevent full rear extension of the leg. To compensate, stiff runners achieve extension by arching their back and tilting their pelvis forward; this shifts the foot strike forward, in front of the runner’s center of mass, and creates an inefficient braking force, as well as a heavy foot strike that takes its toll on ankle, hip, and knee joints, explains USA Triathlon performance adviser Bobby McGee.

This stretch targets the glutes while opening the hips and groin. Start standing up straight; bend your left knee, and bring your foot up behind your hips. Attach a resistance band around your raised foot and hold the ends of the band with both hands. Raise your arms up and over your head as you straighten your bound leg out behind you. Attempt to pull your leg down toward the floor against the resistance of the band. Perform this exercise for 15 seconds before alternating legs.

Honestly, I am new to a lot of this stuff, so I am definitely not an expert on the subject. However, I have been doing some research on the matter, and it seems most people recommend stretching the opposing muscle group in such cases. For example, if you injured your hamstring, you would stretch your thigh. You would also want to stretch the surrounding muscle groups, seeing as how our entire body is fit together, so that every part of your body affects every other part. I realize that by now you are probably back to skating, but for anyone else who reads this and has a similar issue, I would still suggest looking into it a bit, as, like I said, I am new to a lot of stuff (PE was about as far as I got when it came to exercise, until almost two months ago, when I found crossfit), but at least it’s a start.
Athletes with relative shortening of the hip flexors and accompanying weakness of hip extensors will exhibit decreased hip extension at terminal stance phase or “toe off.” Athletes who lack hip extension may also exhibit related limitation in great toe extension. Often these athletes will show decreased wear under the great toe aspect of their shoe sole and relative increased wear under the more lateral toes. These athletes may also demonstrate increased hip flexion at initial contact or “heel strike” in an effort to make up for the shorter stride length caused by limited hip extension. In patients with knee instability this will contribute to hyperextension or “giving way” of the knee.13

Tight hip flexors occur for a variety of reasons. Those who run frequently or engage in other activities that put strain on the hip flexors are likely to experience hip flexor tightness at one time or another. A blow to the hip or poor conditioning can also be causes of tight hip flexors. These causes can usually be attributed to tiny tears that occur to our hip flexors through rigorous activity.

Lay on your back on your mat and pull your knees to your chest. Place your hands on the inside arches of your feet and open your knees wider than shoulder-width apart. Keeping your back pressed into the mat as much as possible, press your feet into hands while pulling down on feet, creating resistance. Breathe deeply and hold for at least 30 seconds.
Then, consider that where there is tightness there might also be weakness somewhere near by. With 11 muscles contributing to the gross movement of hip flexion, it’s possible that some of the muscles are stronger than others. If some are stronger and work harder than others they might get overly tight. Identifying which hip flexors are weak and strengthening them is another way to approach hip flexor tightness.
Putting the exercise in writing do not help me, I need to watch them doing them so, I can figer out how to do them, or if I should even try to do them. I use the flex extendors, lifting my legs one at a time from the flor to strengthen my thys, hip and buttox. And I try to remember to do the bridge excerise. I have had 2 total hip replacements , 7 months a part, in 2013. Trying to get stronger with cold weather will be 70 in Feb. Linda
To complete this stretch, get into the same kneeling position from the half kneeling hip flexor stretch. Whichever leg you have raised, place that hand on your hip. (So, if you’re doing this exercise with your right leg, place your right hand on your right hip, and vice versa.) Next, tighten your glute muscles, and reach around your body with your free hand to grab that foot. Pull that foot upwards towards your upper body
This stretch opens the abductors and deeply opens the hips and lengthens the adductors while improving balance. Stand straight, holding the back of a chair at your left side. Lift your right knee into your chest, and grab hold of your foot with your right hand. Slowly straighten your leg up along your side, into a standing split. Keep your hand on your foot and lean your torso to the left. Hold this pose for 30 seconds before alternating sides.
The more than 20 muscles that make up your hips are responsible for stabilizing your pelvis, moving your legs from side to side, and shortening to draw your knees toward your chest every time you sit down, run, jump or pedal, explains Kelly Moore, a certified yoga instructor and co-founder of Mindfuel Wellness, which brings health and wellness initiatives to companies throughout Chicago.